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AGRICULTURAL  EXPERIMENT  STATION 


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NEW     HAVEN,    CONN. 


BULLETIN   143,    MAY,   1903. 


ENTOMOLOGICAL    SERIES,    No.    9- 


Two  Common  Scalc-lnsccts  of  the  Orchard. 


The  Scurfy  Bark-Louse.    The  Oyster-Shell  Bark-Louse. 


CONTENTS. 

Officers  and  Staff  of  Station 

Two  Common  Scale-Insects  of  the  Orchard. 

The  Scurfy  Bark-Louse .... 

The  03'ster-Shell  Bark-Louse 

Remedies 

Summary 


p  C  E I V  F  n 

4      1903 


U.S.  Dep&»tmento1  Agriculture. 

Paare. 


The  Bulletins  of  this  Station  are  mailed  free  to  all  citizens  of 
Connecticut  who  apply  for  them,  and  to  others  as  far  as  the  limited 
editions  permit 


CONNECTICUT  AGRIGDLTURAL  EIPERIMENT  STATION, 


BOARD    OF   CONTROL. 

Ex  officio. 
His  Excellency  Abiram  Chamberlain,  President. 

Prof.  W.  O.  Atwater  Middletown. 

Prof.  W.  H.  Brewer,  Secretary  New  Haven. 

B.  W.  Collins  Meriden. 

T.  S.  Gold  West  Cornwall. 

Edwin  Hoyt  New  Canaan. 

J.  H.  Webb   Hamden. 

E.  H.  Jenkins,  Director  and  Treasurer  New  Haven. 


STATION    STAFF. 

Chemists. 

Analytical  Laboratory. 

A.  L.  WiNTON,  Ph.B.,  Chemist  in  charge. 

A.  W.  Ogden,  Ph.B.  M.  Silverman,  Ph.B. 

E.  Monroe  Bailey,  Ph.B. 

Laboratory  for  the  Study  of  Proteids. 

T.  B.  Osborne,  Ph.D.,  Chemist  in  charge. 

I.  F.  Harris,  B.S. 

Botanist. 
G.  P.  Clinton,  S.D, 

Entomologist. 
W.  E.  Brixton,  B.S. 

Assistant  to  the  Entomologist. 
B.  H.  Walden,  B.Agr. 

In  charge  of  Forestry  Work. 
Walter  Mulford,  F.E. 

Grass  Gardener. 
James  B.  Olcott,  South  Manchester. 

Stenographers  and  Clerks. 

Miss  V.  E.  Cole. 
Miss  L.  M.  Brautlecht. 

In  charge  of  Buildings  and  Grounds. 
William  Veitch. 

Laboratory  Helpers. 
Hugo  Lange.  William  Pokrob. 

Sampling  Agent. 
V.  L.  Churchill,  New  Haven. 


TWO    COMMON    SCALE-INSECTS.  3 

TWO  COMMON  SCALE-INSECTS  OF  THE  ORCHARD. 

The  Scurfy  Bark-Louse  Chionaspis  furfurus  Fitch. 
The  Oyster-Shell  Bark-Louse  Mytilaspis  poinorum  Bouche. 
By  W.  E.  Britton,  State  Entomologist. 

Long  before  Connecticut  orchards  were  attacked  by  the  San 
Jose  or  pernicious  scale-insect,  the  scurfy  bark-louse  and  the 
oyster-shell  bark-louse  were  present  as  parasites  upon  the  trees 
and  caused  considerable  damage  each  year.  These  orchard 
enemies  still  injure  trees,  though  their  work  has  been  some- 
what overshadowed  by  the  damage  of  the  San  Jose  scale  dur- 
ing the  last  few  years.  The  two  kinds  of  scale-insects 
described  in  this  publication  are  frequently  received  at  the 
Station  and  the  correspondent  usually  asks  if  it  is  the  San  Jose 
scale.  This  bulletin  has  been  prepared  for  the  purpose  of  dis- 
tributing information  about  these  two  common  species  and  the 
remedies  for  them,  as  well  as  to  point  out  wherein  they  differ 
in  appearance  from  the  San  Jose  scale.  The  San  Jose  scale- 
insect  has  three  or  four  broods  each-  year,  is  circular  in  outline, 
and  is  shown  in  figure  i.  The  oyster-shell  and  scurfy  bark- 
lice  are  much  larger,  elongated  or  pear-shaped,  and  single 
brooded.     See  figures  2  and  4. 

The  life  histories  of  the  species  forming  the  subject  of  this 
bulletin  are  so  nearly  alike  that  the  same  remedial  treatment 
answers  for  both. 

The  terms  "scale"  and  'bark-louse"  are  both  applied  to 
insects  of  this  group  {Coccidce)  and  may  be  considered  as 
synonymous  w'ith  the  compound  w'ord  "scale-insect." 

The  Scurfy  Bark-Louse. 

The  scurfy  bark-louse  is  a  native  of  North  America,  and 
was  formerly  called  "Harris'  Bark-Louse."  It  is  now  found 
throughout  the  United  States,  and,  according  to  Howard,  is 
being  succeeded  by  the  oyster-shell  bark-louse.* 

The  female  scale  is  about  3  mm.  (^  inch)  in  length, 
broadly  pear-shaped,  with  the  cast  larval  skin  at  the  smaller 

*  Year-book,  1S94,  U.  S.  Department  of  Agriculture,  p.  259,  Washing- 
ton, D.  C. 


4  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    I43. 

end  which  usually  points  upward.  The  color  is  light  grey  or 
white.  The  male  scale  is  much  smaller  than  the  female,  pure 
white,  with  three  parallel  ridges  along  the  back,  and  parallel 
sides.  Males  and  females  usually  occur  on  separate  twigs. 
Both  sexes  are  shown  in  figure  2. 

There  is  only  one  generation  each  year  in  Connecticut.     The 
eggs  hatch  during  the  latter  part  of  May.     Our  records  show 


Fig.   I. — San  Jos6  scale  on  peach  twig  :    a.  mature  females  :    b.  young 
females  :  c.  immature  males.     About  twice  natural  size. 


that  on  May  19th,  1902,  material  was  brought  to  the  Station 
from  North  Guilford,  and  that  some  of  the  eggs  had  hatched. 
The  writer  has  made  observations  on  this  point  for  several 
years  and  usually  the  eggs  hatch  here  between  May  20th  and 
June  1st. 


THE    SCURFY    BARK-LOUSE. 


5 


The  newly-hatched  insect  (see  figure  3,  c)  crawls  about  for  a 
short  time,  then  becomes  fixed,  forms  a  shell  and  sucks  the  sap 
from  the  tree.  The  female  becomes  mature  during  Septem- 
ber, and  later  dies  and  shrivels  up,  leaving  the  old  shell  filled 
with  oval,  purple  eggs.  Usually  between  thirty  and  fifty  eggs 
are  produced  by  each  female.  In  Connecticut  the  writer  found 
the  eggs  as  early  as  October  ist  in  1900,  while  they  had  not 
been  formed  on  October  9th,  1901.  Usually  they  are  formed 
during  the  first  week  in  October.  Howard  states  that  in  the 
vicinity  of  Washington  the  eggs  are  formed  October  15th 
and  hatch  uniformly  about  the  middle  of  May.*  There  is 
probably  more  than  one  brood  in  the  Southern  States. 


Fig.  2. — Scurf}'  bark-louse  :  a.  c.  females  :  b.  d.  males  .  a.  b.  natural 
size  :  c.  d.  much  enlarged.  (After  Howard,  Year-book  of  U.  S.  Depart- 
ment of  Agriculture  for  1S94.) 


The  chief  injury  caused  by  this  species  occurs  to  young  pear 
and  apple  trees  either  in  nursery  rows  or  in  newly-set  orchards. 
Sometimes  the  bark  of  the  trunk  and  branches  is  entirely  cov- 
ered by  the  grey  shells,  thus  giving  the  tree  the  appearance  of 
having  been  whitewashed.  Such  trees  make  little  growth  and 
are  frequently  killed  outright.  Seldom  do  we  find  the  insect 
abundant  on  large  trees.  Currant  bushes  are  often  infested 
and  mountain  ash  and  hawthorn  are  frequently  attacked  by  the 
scurfy  bark-louse.  The  appearance  of  an  infested  currant 
twig  is  shown  on  Plate  I. 

*  Loc.  cit. 


6        connecticut  experiment  station,  bulletin  i43. 

The  Oyster-Shell  Bark-Louse. 

This  insect  is  well  known  and  occurs  all  over  the  world. 
Europe  is  thought  to  be  its  original  home,  but  it  has  been 
known  to  be  present  in  the  United  States  for  over  one  hundred 
years.  It  is  more  common  at  the  North,  where  it  is  single- 
brooded,  than  in  the  South,  where  two  generations  occur  each 
year. 


Fig.  3. — Scurfy  bark-louse  :  adult  male  above  :  b.  foot :  h.  tip  of  antenna: 
c.  larva  :  d.  antenna  of  larva  :  e.  leg  of  larva  :  f.  pupa  :  g.  adult  female 
with  armor  removed.  All  greatly  enlarged.  (After  Howard,  Year-book  of 
U.  S.  Department  of  Agriculture  for  1894.) 


The  armor  of  the  female  (shown  in  figure  4)  is  about  3  mm. 
(}i  inch)  long,  narrow  and  usually  somewhat  curved,  and  nearly 
the  same  color  as  the  bark  upon  which  it  is  found.  The  cast 
larval  skin  may  be  seen  at  the  pointed  end.  Generally  it  is  darker 
in  color  than  the  scurfy  bark-louse,  as  well  as  narrower.  The 
armor  of  the  male  is  much  smaller  and  less  curved  than  that 
of  the  female.  The  male  scales  are  seldom  seen  upon  fruit 
trees.     The  adult  male  (shown  in  figure  5)  is  provided  with 


THE   OYSTER-SHELL   BARK-LOUSE. 


a  pair  of  wings,  legs,  antennas  and  eyes,  and  resembles  the  male 
of  the  scurfy  bark-louse. 

The  oyster-shell  bark-louse,  like  the  scurfy  bark-louse, 
passes  the  winter  in  the  egg  stage  and  the  small,  oval,  white 
or  pale  yellow  eggs  hatch  about  the  first  of  June  or  a  few  days 
later  than  the  eggs  of  the  scurfy  bark-louse.  The  young  were 
crawling  on  twigs  received  at  the  Station  June  9th,  1902.  As 
many  as  one  hundred  eggs  are  sometimes  laid  by  a  single 
female. 


Fig.  4. — Oj'ster-shell  bark-louse  :  a.  female  scale  from  below  showing 
eggs  :  b.  dorsal  view  of  same  :  d.  male  scale — all  enlarged  :  c.  females  ,  e. 
males — natural  size  on  twigs.  (After  Howard,  Year-book  of  U.  S.  Depart- 
ment of  Agriculture  for  1894.) 

No  observations  have  been  made  by  the  writer  regarding  the 
time  when  the  eggs  are  laid  in  the  fall,  but  eggs  were  formed  in 
specimens  collected  in  December.  According  to  Smith  the 
eggs  are  formed  late  in  August  and  during  September.* 

The  oyster-shell  bark-louse  is  found  on  nearly  every  old 
apple  tree  in  Connecticut,  and  may  occur  on  the  small  twigs 
*  Bull.  140,  New  Jersey  Exp.  Station,  p.  5. 


CONNECTICUT    EXPERIMENT    STATION^    BULLETIN    I43, 


and  on  the  large  branches  and  trunk  in  the  crevices  of  the 
rough  bark.  It  weakens  trees  unquestionably,  but  the  writer 
has  never  seen  fruit  trees  killed  by  the  oyster-shell  bark-louse 
in  Connecticut.  Many  seedlings  and  sprouts  of  native  trees 
in  fields  and  woods  are  killed  each  year  by  it.  Ash,  poplar, 
willow,  birch,  butternut,  black-walnut  and  maple  are  the  trees 
most  commonly  injured,  and  are  frequently  infested  to  such 
an  extent  that  no  portion  of  the  bark  can  be  seen. 


Fig.  5. — Oyster-shell  bark-louse:  a.  adult  male:  b.  foot:  c.  larva;  d. 
antenna  of  larva  :  e.  adult  female  with  armor  removed.  All  greatly  en- 
larged. (After  Howard,  Year-book  of  U.  S.  Department  of  Agriculture 
for  1894.) 

In  nurseries  and  ornamental  plantations  lilac,  Kilmarnock 
willow  and  some  species  of  Elceagniis  are  often  seriously 
infested. 

The  appearance  of  twigs  and  branches  infested  by  the 
oyster-shell  bark-louse  is  shown  on  Plate  II. 

Remedies. 

The  eggs  of  both  the  scurfy  and  the  oyster-shell  bark-lice 
are  hard  to  kill,  so  that  winter  applications  are  not  effective  in 


REMEDIES.  9 

fighting  the  species.  Some  writers  advise  a  winter  application 
of  whitewash  to  destroy  them :  this  frequently  causes  the  shells 
to  fall  from  the  bark  and  the  eggs  are  scattered,  and  perhaps  to 
such  an  extent  that  the  young  are  not  able  to  reach  the  tree. 
But  many  eggs  remain  on  the  tree  and  are  not  injured  by  the 
whitewash.  Frequently  these  eggs  withstand  applications  of 
kerosene  and  crude  oil.  The  most  vulnerable  point  in  the  life 
history  of  both  species  is  just  after  the  eggs  hatch,  while  the 
young  are  crawling  and  before  they  have  become  protected  by 
the  formation  of  their  shells  or  armor.  In  Connecticut  this 
period  occurs  during  the  first  half  of  June,  and  the  newly- 
hatched  insects  may  be  destroyed  readily  by  spraying  with  any 
of  the  common  contact  insecticides.  Common  soap  and  water 
(i  lb.  dissolved  in  8  gallons)  is  as  convenient  as  any  applica- 
tion and  is  cheap  and  efifective.  Any  laundry  soap  will  answer. 
It  should  be  cut  in  thin  slices,  dissolved  in  boiling  water  and 
diluted  to  make  the  proper  proportions.  Whale-oil  soap  in  the 
same  proportions  can  also  be  used.  Kerosene  emulsion  is 
recommended,  and  a  mechanical  mixture  of  kerosene  and 
water,  containing  from  lo  to  15  per  cent,  of  kerosene,  applied 
with  a  "  Kerowater"  pump  is  also  a  cheap  and  satisfactory 
remedy. 

Summary. 

1.  The  scurfy  bark-louse  and  the  oyster-shell  bark-louse 
have  commonly  injured  fruit  trees  for  many  years  in  Connecti- 
cut by  sucking  out  the  sap  and  are  often  mistaken  for  the  San 
Jose  scale-insect,  which,  on  account  of  a  different  life-histort, 
must  receive  different  treatment. 

2.  The  scurfy  bark-louse  is  a  native  of  North  America  and 
is  well  distributed  over  the  United  States.  The  female  is  light 
grey  and  pear-shaped,  while  the  male  is  much  smaller,  white 
with  parallel  sides.  There  is  one  brood  each  year  at  the  North. 
It  winters  in  the  egg  stage  and  the  eggs  hatch  during  the  latter 
part  of  May.  Eggs  for  the  next  brood  are  laid  the  first  week 
in  October.  Small  apple  and  pear  trees  and  currant  bushes 
are  the  most  seriously  infested  and  are  sometimes  killed. 

3.  The  oyster-shell  bark-louse  is  found  all  over  the  world, 
and  was  probably  introduced  into  this  country  from  Europe 
more  than  a  hundred  years  ago.      It  is  darker  in  color  and 


10         CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    I43. 

narrower  than  the  scurfy  bark-louse ;  the  hfe  history  is  very 
similar,  but  the  eggs  are  a  few  days  later  in  hatching,  and  are 
formed  earlier  in  the  fall.  There  is  one  brood  each  year.  It 
infests  apple,  but  is  common  on  ash,  poplar,  willow,  butternut 
and  lilac,  often  killing  them. 

4.  Spraying  the  trees  during  the  first  two  weeks  in  June,  or 
while  the  young  are  crawling,  with  soap  and  water  (i  lb.  in  8 
gals.)  or  with  kerosene  emulsion  will  readily  destroy  the  newly- 
hatched  larvae. 


PLATE  I. 


SCURFY  BARK-LOUSE   Chiouaspis  furfurns  Fitch. 
Females  on  currant.     Natural  size. 


PLATE   II. 


yV^^:, 


OYSTER^SHELL  BARK-LOUSE  Mylilaspis  pomorum  Bouclie. 
Females  on  poplar.     Natural  size. 


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